Patent GB-316582-A (GB)
Abstract: 316,582. Weemhoff, C. A. July 31, 1928, [Convention date]. Plane-trigonometry calculators.-A directing device for use in bomb dropping from aircraft comprises four arms 1, 5, 8, 13, Fig. 1, jointed together to form a quadrangle representing respectively the speed of the aircraft, the speed of the wind, the speed of the target, and the relative speed between aircraft and target. The arm 1 is formed with a slot 2, in which a spindle 3 is adjustably clamped, so that the vector 11-3 represents the speed of the aircraft. The arm 5 and a course circle 4 are pivoted about the spindle 3, and a spindle 7 is adjustable along the arm 5, so that the vector 3-7 represents the speed of the wind. The arm 8 is pivoted on the spindle 7, and a spindle 10 is adjustable along the arm 8, so that the vector 7-10 represents the speed of the target. The arm 13 is pivoted on the spindle 10 and is formed with a slot 14 guided by the spindle 11 on the arm 1, so that the vector 10-11 represents the relative speed. Other arms may be added as follows : An arm 23 is pivoted with a guide block 22 about the spindle 11; the arm 13 slides in the guide block 22, so that the arm 23 rotates with the arm 13 about the pivot 11 and a groove 24 along the arm 23 is maintained at right-angles to the arm 13. Another arm 25 is pivoted on the spindle 11 and is adjustable at an angle to the groove 24 corresponding to the lag of the bomb. This angle is shown by a spring pawl 28 on the arm 25 against an arm 29-30 on the arm 23. A pointer 27 is adjustable with a sliding block along the arm 25 and is set to a scale along the groove 24 corresponding to the height of the aircraft. An arm 35 is pivoted on the spindle 10 and when in line with a point 36 on the pointer 27 determines the moment when the bomb must be dropped. The contact of the arm 35 with the point 36 may close a switch causing the automatic release of the bomb. An arm 18 is pivoted on the spindle 10, and on this arm is adjusted a spindle 20 guided by the slot 2 of the arm 1. The distance 10-20 is adjusted to correspond to the speed of the aircraft, so that when the vectors 3-7 and 7-10 are set, an observation of a target may be made to determine the angle of the arm 18 relatively to a sector 21 concentric with the pivot 20 but non-rotatable with respect to the arm 1. This angle being then used to set the course of the aircraft. The directing device may be connected to a sighting device by means of Bowden wires a, b. The Bowden wire a is guided by an arc 15 carried by the arm 1 and concentric with the pivot 11; and the wire is attached to a block 31 riding on that arc and sliding over the arm 13. Similarly the Bowden wire b is guided by an arc 32 carried by the arm 13 and concentric with the pivot 10; and the end of the wire is attached to a block 33 riding on the arc and sliding over the arm 35. The other end of the Bowden wire a is similarly attached to a block 42, Fig. 2, riding on a circular arc 37 on the fixed part 38 of a Zeiss bomb-directing apparatus; and the block 42 moves according to the angle of leeway with the arm 41 of the rotatable part 40 of the apparatus. The other Bowden wire b is similarly connected to a block 47 riding on an arc 43 with an arm 45 of the ring 46, which is adjusted for angle of deflection for travel of target.